Juvenile Case

In some cases yes and in some cases no that punishment does deter juveniles

It all really depends on the individual. Some kids literally have brain damage from maternal alcohol or drug consumption when they were in the womb. Other kids have abused drugs to the point that their brains are damaged. Some have such extensive trauma in their past that they no longer operate emotionally or logically the way others do, and punishment in their mind just reinforces beliefs that they are worthless, which doesn't help anything. But some kids hate their punishments so much that the threat of it sets them straight. (Eric J. Fritsch, Tory J. Caeti, and Craig Hemmens, "Spare the Needle But Not the Punishment: The Incarceration of Waived Youth in Texas Prisons," Crime and Delinquency, vol. 42 (1996), p. 593.)

From a policy standpoint, the question is whether the punishment deters enough kids that the money spent on the punishment is cost-effective compared to a different approach, such as treatment. Legislators and administrators often follow cost-benefit analyses. so long as the juvenile believes the punishment will be enforced and rules/laws against it will become more strict if the action is repeated. I believe that yes it does

To date, only two studies have examined whether stricter transfer laws result in lowered juvenile crime rates. Both found that there was no evidence to support that the laws had the intended effect. Criminologists Simon Singer and David McDowell evaluated the effects of New York's Juvenile Offender Law on the rate of serious juvenile crime. This landmark piece of legislation was passed in 1978, and lowered the age of criminal court jurisdiction to thirteen for murder, and to fourteen for rape, robbery, assault, and violent categories of burglary. Singer and McDowell analyzed juvenile arrest rates in New York for four years prior to the enactment of the law, and six years after. These rates were compared with those for control groups of thirteen and fourteen year olds in Philadelphia, and with slightly older offenders in New York. The researchers found that the threat of adult criminal sanctions had no effect on the levels of serious juvenile crime. Singer, Simon I., and David McDowall. 1988. "Criminalizing Delinquency: The Deterrent Effects of the New York Juvenile Offender Law." Law and Society Review 22:521-35; cited in "Bishop, Donna, "Juvenile Offenders in the Adult Criminal System," 27Crime and Justice 81 (2000)

A later study by social scientists Eric Jensen and Linda Metsger reached a similar conclusion. They sought to evaluate the deterrent effect of the transfer statute passed in Idaho in 1981, which required that juveniles charged with certain serious crimes (murder, attempted murder, robbery, forcible rape, and mayhem) be tried as adults. They examined arrest rates for five years before and five years after the passage